difficult one, analysing the data is when you get to realise what is true and what is not. So I guess this question is also a way of asking what is the most interesting finding I have made. One thing which really surprised me, was when we trained cats to find food on the other side of a cat flap, and they could use either a visual or smell cue, e.g there might be a red dot smelling of strawberries to indicate where the food could be found and a yellow dot smelling of bananas where there was no food. We then crossed the cues, i.e made the red dot smell of bananas and yellow dot smell of strawberries. we then watched to see where the cats went and found to our surprise they used the visual not the smell cue.
see details here: http://www.sciencedirect.com/science/article/pii/S0168159115000210